Power mechanism



Sept. 30, 1930. R, o so Q 1,777,056

POWER MECHANISM Original Filed April 25, 1928 Patented Sept. 30, '1930 UNITED STATES PAT ENT OFFlCE RUSSELL G. THOMPSON, OF ROCHESTER, NEW YORK, ASSIGNOR TO ELECTROMATIC TYPEWRITERS, INQ, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK POWER MECHANISM Application filed April 2a, 1928, Serial No. 272,155. Renewed January 9, 1930.

This invention relates to power mechanism designed particularly for use in actuating the type bars or corresponding members of a typewriting machine, by power under the control of.key levers, or the like, operated either manually or automatically. The mechanism herein described is also suitable, however, for use in machines of other kinds wherein a series of members are to be operated selectively by power.

The invention relates particularly to power mechanism of the type disclosed in- United States Letters Patent to J. F. Smathers, No. 1,600,252, wherein each type bar is actuated by a power unit comprising a cam pivotally mounted on a lever and arranged to have a rolling engagement with a constantly rotary power-driven roller. One object of the 1nvention is to produce a cam mechanism of th1s 30 type in which the construction is particularly simple, compact, durable and inexpensive.

To this end the parts are so rearranged as to comprise two cams of similar form, pivoted on opposite sides of a cam lever which comprises a single piece of sheet metal, in place of the single wide .cam pivoted between two lever members, as in said Smathers patent. To the same end, other novel details of construction are used, which will hereinafter be pointed out.

In a power mechanism of the type ln'question a very slight movement of the key lever may be caused to operate the means by which the operation of cam is controlled, but, some users find such an arrangement too delicate for convenient operation, and prefer an arrangement in which a greater movement or dip of the key lever is provided for. A second object of the present invention is to permit the ,use of a greater key lever movement than is actually necessary, and preferably to provide for a ready adjustment of the amount of such movement, to suit the individual operator, without any disturbance of the functional relation of the other parts of the mechanism. To this'end it is proposed to in terpose between the cam-controlling member and the key lever a connection having provision for lost motion, but to so arrange the cam-controlling member that it still operates with only the necessary amount of movement,

- so that repeated releases of the same cam may be accomplished without the necessity of permitting the key lever to return fully to raised position between successive cam operations.

In the accompanying drawings, Fig. -1 is a side elevation, partly in section, of power mechanism embodying the presentin'vention, including the power roller, one cam-unit and the key lever by which it is controlled. Fig. 2 is a side elevation of the cam-unit, seen from the opposite direction from Fig. 1. Figs. 3 and 4 are side elevations, on an enlarged scale, of the two cams embodied in one cam unit, seen from the sides adjacent the cam lever. Fig. 5 is a front elevation of the camunit shown in Fig. 1, and Fig. 6 is a section on the line 66 in Fig. 2, looking from left to right and on a larger scale than said figure.

The invention is illustrated as embodied in mechanism comprising a power roller 10, which may be made of any suitable frictional material, and which is rotated constantly in the direction of the arrow in Fig. l by connection with any suitable 'source of power. Two cams, 20 and 21, of similar form, are pivoted upon the depending arm of a bellcrank lever 12 which comprises a single flat piece of sheet metal. This lever is hereinafter referred to as the cam lever. The cam lever is pivotally mounted upon a rod 13, supported by a horizontal frame member 14. This member may be slotted to receive each of the cam levers, in a manner familiar in themanufacture of typewriting machines. The

horizontal arm of each cam lever is connected, by a link 15, with the corresponding type bar or other member of the machine (not shown) which is to be actuated.

Each cam-unit is controlled by a key lever 16, carrying a manually operable key 17. The key levers are mounted upon a pivot rod 18, supported by a horizontal frame member 19. The forward end of the key lever is guided by a slotted guide-bar 40, and a spring 37 tends to raise the lever in the guide. A stop plate 38, secured adjustably to the guide-bar by means of bolts 39,'limits the upward movement of the lever. 4

The cams 20 and 21 are similar in outline,

each comprising two lobes of increasing racam lever is swung in a direction to pull upon the link 15. The cams are fixed on opposite ends of a pivot 24,,which has an enlarged central portion 25 turning in a bearing in the cam lever, as shown in Fig. 6. This pivot not only supports the cams, but maintains them rigidly in corresponding position, so that they act as one member.

Owing to the fact that the cams have equal width and are located at equal distances on opposite sides of the lever, they have no tendency to tilt out of position when pressed against the roller, and thus friction in the cam bearing is minimized. Since the cam lever lies at all points in a plane including the lines of the forces transmitted through it, a single piece of sheet metal of no great thickness may be used to transmit a considerable amount of power, and the construc tion of the cam-unit is thus simplified and cheapened without loss in efiiciency.

In order to attain the maximum compactness in the cam-unit, the cam-controlling members are arranged close to the sides of the cam lever, so that they may work in the spaces between the cams and the lever. The cam 21 has a hub portion 23 of elongated form. with rounded ends. This cooperates with a spring lever 26, which is mounted loosely upon a pivot 11, arranged to turn in an opening in the cam lever. The pivot has an enlarged head 27, upon which a spring 28 is coiled. One end of this spring is attached to the cam lever, as shown in Figs. 1 and 2, while the opposite end engages an arm 11 on the spring lever and tends to rock this lever in a direction to press it against the hub 23. In the normal inactive position of the cams, as shown in Figs. 1 and 2, the engagement just described tends to impart a partial rotation to the cams in a direct-ion to cause their lower lobes to come into engagement with the power roller. Such rotation is normally prevented, however, by detent mechanism comprising a lever 29, which is fixed to the end of the pivot 11 at the opposite side of the cam lever from that on which the spring lever lies. The dctent lever carries, at its lower end, two detents in the form of lugs 30 and 31, which cooperate with two oppositely disposed stop lugs 32 on the cam 20. Normally, one or the other of these stop lugs rests upon the upper'surface of the detent 30, and thus prevents rotation and operation of the cams.

At its upper end, the detent lever has :1. lug 33 which projects laterally through a hole 34 in the cam lever. This lug is embraced by the forked extremity 35 of the depending arm of the key lever 16. When the key 1 is depressed the key lever acts to swing the detent lever in a direction to move the detent 30 outwardly from engagement with the stop lug 32. The cams thereupon perform a half rotation in engagement with the power roller, but they .are arrested, at the end of this operation. by engagement of the other stop lug 32 with the detent 31. Upon the release and return of the key lever, the detent lever swings back to normal position, thus disengaging the detent 31 from the stop lug. The cams then make a slight turning movement, under the influence of the spring lever, by which the stop lug which at that time is in operative position moves into engagement with the detent 30, the parts being thus restored to position for another cycle of operation.

The lostanotion connection hereinhei'tmreferred to is provided by making the ICitsrt in the extremity 35 of the kev lever suhstan tially wider than the lug 353 on the detent lever, and by providing a spring 36, which returns the detent lever to normal position independently of the action of the spring 37 by which the key lever is returned. This spring 36 is attached, at one end, to the cam lever and, at the other end, to an arm or projection 42 on the detent lover. The nor mal position of the detent lever is determined by engagement of the lug 33 with the edge of the hole 31 in which it moves.

It will be apparent that the arrangement just described is such that the key lever, when depressed, has a certain amount of idle movement at first, until the lost motion has been taken up between its forked extremity and the lug 33. The amount of this motion, and thus the total movement of the key lever, may be adjusted by means of the stop plate 38. The last part of the downward movement of the key lever is that which is effective to release the cams. Upon the return movement of the key lever, however, it is the first part of the movement which is effective to permit the spring 36 to restore the detent lever to normal position. Accordingly, where rapid repetition of the operation of the same cam-unit is required, it is not necessary to permit the key lever to return fully to normal position: an upward movement long enough only to permit the disengagement of the stop lug 32 from the detent 31 is s'uflicient.

The invention claimed is:

1. In power mechanism of the type set forth, the combination of a cam-actuated lever, two cams of similar outline, on opposite sides of the lever, and a pivot rigidly con necting the cams in parallel position and journalled in the lever.

2. In power mechanism of the type set forth, the combination of a cam-actuated lever, two cams of similar outline, on opposite sides of the lever, a pivot journalled in the lever and rigidly connecting the cams in parallel position, a control projection on one of 1 i the cams, on the side toward the lever, and a control member,- cooperatin with said projection and movably mounted upon the side of the lever. v,

3. In powermechanism of the type set forth, the combination of. a cam-actuated lever, two cams, of similar outline, on opposite sides of the lever, a pivot journalled in the lever and rigidly connecting the cams in parallel position, the cams being spaced away from the sides of the lever, control projections extending from theinner sides of the cams, and two control members movably mounted on the lever on opposite sides thereof, extending into the spaces between the lever and the respective cams and cooperating with said proj ections-on the cams.

4. In power mechanism of the type set forth, the combination of a. cam lever, a cam journalled thereon, a control member, cooperative with the cam, movably mounted on the cam lever, a return spring and a return stop for the control member, a ke lever having a lost-motion connection wit saidcontrol member, and an independent return spring for the key lever. c

5. The combination set forth in claim 4, with the addition of an independent return stop for the ke' lever. J

RU SSELL G. THOMPSON. 

